float
powf(float x, float y) /* wrapper powf */
{
#ifdef _IEEE_LIBM
return __ieee754_powf(x,y);
#else
float z;
z=__ieee754_powf(x,y);
if(_LIB_VERSION == _IEEE_|| isnanf(y)) return z;
if(isnanf(x)) {
if(y==(float)0.0)
/* powf(NaN,0.0) */
return (float)__kernel_standard((double)x,(double)y,142);
else
return z;
}
if(x==(float)0.0){
if(y==(float)0.0)
/* powf(0.0,0.0) */
return (float)__kernel_standard((double)x,(double)y,120);
if(finitef(y)&&y<(float)0.0)
/* powf(0.0,negative) */
return (float)__kernel_standard((double)x,(double)y,123);
return z;
}
if(!finitef(z)) {
if(finitef(x)&&finitef(y)) {
if(isnanf(z))
/* powf neg**non-int */
return (float)__kernel_standard((double)x,(double)y,124);
else
/* powf overflow */
return (float)__kernel_standard((double)x,(double)y,121);
}
}
if(z==(float)0.0&&finitef(x)&&finitef(y))
/* powf underflow */
return (float)__kernel_standard((double)x,(double)y,122);
return z;
#endif
}
/* wrapper powf */
float
__powf (float x, float y)
{
float z = __ieee754_powf (x, y);
if (__builtin_expect (!__finitef (z), 0))
{
if (_LIB_VERSION != _IEEE_)
{
if (__isnanf (x))
{
if (y == 0.0f)
/* pow(NaN,0.0) */
return __kernel_standard_f (x, y, 142);
}
else if (__finitef (x) && __finitef (y))
{
if (__isnanf (z))
/* pow neg**non-int */
return __kernel_standard_f (x, y, 124);
else if (x == 0.0f && y < 0.0f)
{
if (signbit (x) && signbit (z))
/* pow(-0.0,negative) */
return __kernel_standard_f (x, y, 123);
else
/* pow(+0.0,negative) */
return __kernel_standard_f (x, y, 143);
}
else
/* pow overflow */
return __kernel_standard_f (x, y, 121);
}
}
}
else if (__builtin_expect (z == 0.0f, 0) && __finitef (x) && __finitef (y)
&& _LIB_VERSION != _IEEE_)
{
if (x == 0.0f)
{
if (y == 0.0f)
/* pow(0.0,0.0) */
return __kernel_standard_f (x, y, 120);
}
else
/* pow underflow */
return __kernel_standard_f (x, y, 122);
}
return z;
}
static float
gammaf_positive (float x, int *exp2_adj)
{
int local_signgam;
if (x < 0.5f)
{
*exp2_adj = 0;
return __ieee754_expf (__ieee754_lgammaf_r (x + 1, &local_signgam)) / x;
}
else if (x <= 1.5f)
{
*exp2_adj = 0;
return __ieee754_expf (__ieee754_lgammaf_r (x, &local_signgam));
}
else if (x < 2.5f)
{
*exp2_adj = 0;
float x_adj = x - 1;
return (__ieee754_expf (__ieee754_lgammaf_r (x_adj, &local_signgam))
* x_adj);
}
else
{
float eps = 0;
float x_eps = 0;
float x_adj = x;
float prod = 1;
if (x < 4.0f)
{
/* Adjust into the range for applying Stirling's
approximation. */
float n = __ceilf (4.0f - x);
x_adj = math_narrow_eval (x + n);
x_eps = (x - (x_adj - n));
prod = __gamma_productf (x_adj - n, x_eps, n, &eps);
}
/* The result is now gamma (X_ADJ + X_EPS) / (PROD * (1 + EPS)).
Compute gamma (X_ADJ + X_EPS) using Stirling's approximation,
starting by computing pow (X_ADJ, X_ADJ) with a power of 2
factored out. */
float exp_adj = -eps;
float x_adj_int = __roundf (x_adj);
float x_adj_frac = x_adj - x_adj_int;
int x_adj_log2;
float x_adj_mant = __frexpf (x_adj, &x_adj_log2);
if (x_adj_mant < (float) M_SQRT1_2)
{
x_adj_log2--;
x_adj_mant *= 2.0f;
}
*exp2_adj = x_adj_log2 * (int) x_adj_int;
float ret = (__ieee754_powf (x_adj_mant, x_adj)
* __ieee754_exp2f (x_adj_log2 * x_adj_frac)
* __ieee754_expf (-x_adj)
* __ieee754_sqrtf (2 * (float) M_PI / x_adj)
/ prod);
exp_adj += x_eps * __ieee754_logf (x_adj);
float bsum = gamma_coeff[NCOEFF - 1];
float x_adj2 = x_adj * x_adj;
for (size_t i = 1; i <= NCOEFF - 1; i++)
bsum = bsum / x_adj2 + gamma_coeff[NCOEFF - 1 - i];
exp_adj += bsum / x_adj;
return ret + ret * __expm1f (exp_adj);
}
}
